A high energy radiation system generally has a radiation source, a collimator for collimating the rays emitted from the radiation source into a sector-shape beam, a sensor for detecting the position of a moving object, a radiation detector, a radiation imaging device, a radiation shielding apparatus, etc. Such type of high energy radiation system is utilized to automatically scan an object moving with high speed, such as a vehicle, for inspection, and can accomplish a security check for smuggling, illegal and prohibited objects without interrupting the passing of the vehicles with high speed, and is an ideal means used to implement a security check to vehicles and cargoes.
During radiation inspection on vehicles moving with high speed, it is necessary to avoid radiating and scanning the portion of the vehicle containing persons. Generally, the radiation source emits rays after the driving cab passes the scanning position, and the rays scan only the cargo carriage behind the driving cab, rather than scanning the driving cab, thereby ensuring that the driver can be protected from radiation damage. As a result, the radiation system however cannot scan the vehicle driving cab (such as the vehicle head of a cargo truck) and completely cancels the scanning for some passenger carrying vehicles (such as a bus with a high density of passengers therein). Therefore, an inspection on the whole vehicle may not be performed, causing a potential security risk.